1. Field of the Invention
The present invention relates to an ultrasonic probe capable of transmitting an ultrasonic vibration from a proximal direction toward a distal direction, and an ultrasonic treatment instrument including the ultrasonic probe.
2. Description of the Related Art
Jpn. PCT National Publication No. 2010-522034 discloses an ultrasonic treatment instrument including an ultrasonic probe capable of transmitting an ultrasonic vibration from a proximal direction toward a distal direction. A probe body portion extending along a longitudinal direction is provided in the ultrasonic probe. A distal treatment portion configured to treat a treated target such a living tissue by use of the transmitted ultrasonic vibration is provided in a distal portion of the ultrasonic probe. A plate-shaped portion (blade portion) is provided in the distal treatment portion. The distal end of the ultrasonic probe is formed by the plate-shaped portion. Certain two directions perpendicular to (intersect with) the longitudinal direction and opposite to each other are width directions, and two directions perpendicular to the longitudinal direction and perpendicular to the width directions are thickness directions. In the plate-shaped portion, a width dimension in the width directions is larger than a thickness dimension in the thickness directions. In the plate-shaped portion, an edge surface which is formed from a side edge facing in the width directions and a distal edge facing in the distal direction are provided, and a blade portion is provided in the edge surface. A sectional area decrease portion is continuous between the probe body portion and the plate-shaped portion in the longitudinal direction parallel to a longitudinal axis. In the sectional area decrease portion, the thickness dimension in the thickness directions decreases from the proximal direction toward the distal direction, and a sectional area perpendicular to the longitudinal axis decreases from the proximal direction toward the distal direction. In a state where the ultrasonic probe (treatment portion) vibrates in response to the ultrasonic vibration, the blade portion of the plate-shaped portion is brought into contact with the treated target, and the treated target is thereby cut open. In a state where the ultrasonic vibration is transmitted, the ultrasonic probe performs a longitudinal vibration whose vibration direction is parallel to the longitudinal axis.